Welcome to Physics 1161!

1. Welcome to Physics 1161! • Electricity & Magnetism (E&M) • Optics • Quantum Physics • Atomic Physics • Nuclear Physics • Relativity http://www.smartphysics.com

2. Instructor • Cherie Bibo Lehman • cblehman@eiu.edu • Please include course number in the Subject Line • 1112 Physical Science – (c) 217.251.3734 • Office Hours • T: 1:00 PM – 2:00 PM • W: 10:00 AM – 12:00 PM • R: 1:30 PM – 2:30 PM http://ux1.eiu.edu/~cblehman/

3. Grade Components • Prelectures 05% • Checkpoints 05% • Class Participation*10% • Homework & Quizzes25% • Hour Exams (highest 3 of 4)30% • Final Exam 25% 100% *Based on clicker responses

4. 90-100 A 80-89 B 70-79 C 60-69 D <60 F Grading Scale

5. SmartPhysics • http://www.smartphysics.com • Online prelectures, checkpoints, and homework found there. • You will setup your password when you register for an account. Your logon is your EIU email. For example, my logon is cblehman@eiu.edu • Once you have set up an account, click on the Enrollments tab. • Course access key: lehman2 • The unique identifier can be your name. • DO NOT ever contact SmartPhysics for tech support. Always contact me.

6. Pre-Lectures • Completing the Pre-Lectures will be 5% of your grade. • 24 hours prior to each class, I will post on the SmartPhysics schedule a link to a pre-lecture power point or movie. • You should • go through the pre-lecture • read the relevant sections in the text before you move on to the checkpoint.

7. Checkpoints • Complete the checkpoints - 5% of your grade • 2 points (full credit) for honest attempt at preflight. • Must do the entire preflight to earn any credit, including responding to questions about what you find most interesting or most difficult. • Click on link from Schedule Page. • Checkpoints are due by 6am the day of lecture – with the exception of checkpoint 1 which is due Tuesday night at 11pm

8. Homework • Credit for a problem is awarded when you submit the correct answer. • You can work a problem as many times as needed in order to obtain full credit. • After the due date, you will have 7 days to submit the homework for 80% credit. • Homework is due by 11pm on the due date.

9. PHY1161 Lectures • Not everything you need! • Untangling and clarification of concepts & processes • Comprehensive Textbook • Calculations Homework + Discussion • Hands-On Lab • Taking Notes • Lecture note handouts will be available online prior to class • Key pieces for you to fill in

10. Origin of Charge • Charge is an intrinsic property of matter • Two types: • Positive Charge: Protons • Negative Charge: electrons • Opposites Attract! (likes repel) • Atoms are neutral • Negatively charged electrons “orbit” r~10-10 m • Positively charged central nucleus r~10-15 m

11. Q: How do electrons behave in a perfect conductor? Q: How do electrons behave in a perfect insulator? Conductors and Insulators Most things are in between perfect conductor / insulator

12. Conductors & Insulators • Insulators: In these materials, once they are charged, the charges ARE NOT FREE TO MOVE. Plastics, glass, and other “bad conductors of electricity” are good examples of insulators. • Conductors: In these materials, the charges ARE FREE TO MOVE. Metals are good examples of conductors.

13. Charge • Standard unit of charge Coulomb (C) Coulomb is a huge unit of charge Charge on one electron or proton is: 1.602 x 10-19C – often given letter e A small spark between your finger and a door knob on the order of microcoulombs µC = 10-6C Helium atom

14. Electroscope • Conduction • Charged rod is brought near scope • Charged rod touches scope transferring some charge • Scope is left w/ same charge as rod • Induction • Charged rod is brought near scope • Scope is briefly grounded allowing charge to flow on (or off) scope • Scope is left w/ opposite charge as rod

15. A negatively charged rod is used to charge an electroscope by induction. What is the resulting net charge on the electroscope? • Positive • Zero • Negative

16. If the conducting electroscope were replaced by an insulating ball and then charged by induction as above, what would be the net charge on the ball. • Positive • Zero • Negative

17. q1 q2 r Law of Electrical ForceCharles-Augustin Coulomb(1736 - 1806) " The repulsive force between two small spheres charged with the same sort of electricity is in the inverse ratio of the squares of the distances between the centers of the spheres"

18. Coulomb's Law q1 q2 MKS Units: • rin meters • qin Coulombs • in Newtons k = 9 · 109 N-m2/C2 Coulomb’s constant

19. ® ® ® F = F + F 1 2 Summary • Charges come in two varieties • negative and positive • in a conductor, negative charge means extra mobile electrons, and positive charge means a deficit of mobile electrons • Coulomb Force • Law of Superposition

20. Gravitational vs. Electrical Force F F q1 m1 q2 m2 r ® q q 1 1 2 F = 1 elec pe r 2 4 0 pe 4 F q q elec 1 2 0 m m 1 2 = F m m G F = G grav 1 2 grav r 2 For an electron: ® F + 42 * |q| = 1.6 ´ 10-19 C elec = ´ 4 . 17 10 F m = 9.1 ´ 10-31 kg grav * smallest charge seen in nature!

21. Qp=1.6x10-19 C Qe = -1.6x10-19 C + - r = 1x10-10 m In the picture below, what is the direction of the force on the proton due to the electron? • Left • Right • Zero

22. qp=1.6x10-19 C qe = -1.6x10-19 C + - r = 1x10-10 m F • What is the magnitude of the force on the proton due to the electron? F= _______ N

23. qp=1.6x10-19 C qe = -1.6x10-19 C + - r = 1x10-10 m F • What is the magnitude of the force on the proton due to the electron? F= 2.3 x 10-8N

24. A positive and a negative charge with equal magnitude are connected by a rigid rod, and placed near a large negative charge. What is the direction of the net force on the two connected charges? • Left • Zero • Right Positive charge is attracted (force to left) - Negative charge is repelled (force to right) + - Positive charge is closer so force to left is larger.

25. To Do • Purchase your clicker. • Read Sections 19-1 -- 19-5 • Do checkpoint 1 before 6:00 AM 1/10/13. • Watch PreLecture-2 before 6:00 AM 1/10/13. • Do checkpoint 2 before 6:00 AM 1/10/13. See you next time!